Production of high octane number aviation gasoline



K. M. PURDY :May 17, 1949.

PRODUCION OF HIGH OCTANE NUMBER AVIATION GAASOLINE LlLh ` Filed Oct. 29, 1947 Kmarzeiz 17273141115( 'Javentor Patented May 17, 1949 UNITED STATES PRODUCTION OFHIGHiOCTA-NE `NUMBER. AVIATION GASOLINE- Kenneth M. Purdy, Baton Bouge, La., assigner Ato Standard Oil Development..Company,.a corpo-f ration of Delaware Application Octoberll, 1947, Serial No. 782,735

(Cl. 19E-49) 4 Claims.

l This .invention Ipertains to the iproduction of motor fuels and particularly to thezproduction of high octanevnumberaviation gasoline from hydrocarbonV feed -.stocks of substantially different characteristicsy by `anv integrated vprocess in which light gas oilis catalytically.cracked'under cer.-

tainirelatively mild conditions while `gas oil is subjected .to a catalytic @cracking under more Avrigorous cracking lconditions and blendingV together separate fractions from each of these cracking operations.

Catalytic cracking of lightgas oil! to obtain high .Joctane'aviation gasoline has been diilcult to carry "out since the temperature of 4vcracking must be kept quite low and conversion levels must also be kept fairly low. Even by controlling the tem- 1 CRC'Knock' Testing Manual-1946 edition.

The catalytic cracking of. heavy gas oil` to form high octane aviation. gasoline has not offered the saine problem as the cracking of light gasoil since temperatures can be considerablyhigher and conversion levels can also be quite high. The 325" E. en d point product'formed has good gravity, a very'low Aniline Point but has a very high acid heat. Moreover, while 3C rich mixture performance is somewhat better than that of the comparable product obtained from light gasoil, A. SJTJM. octane number of `the unleaded as well afsithejleaded fuel is below that of the product .obtainedfrom theY catalytic ycracking of light gas oils .at;low temperature and low 4conversion. levels.

I havenowfound that surprisingly if the catalyticcracking of light gasoil'iscarried out at low temperature and low conversion levels as described above and the catalytic cracking of regular or"heavy gas oil is carried out at high temperatures and high conversion levels and a Cs to about V230 F.fraction is taken from the product of the lightigas oil cracking and Vcombined with a 230 F. tof'final aviation boilingpoint (325 F.) fraction taken from the product of thev heavy gasoil cracking, a blended productis obtained which posesses ...properties which` are substantially superior toithose of the productsof either of the separate cracking operations.

:The `light `g-as...oils` which may be used intaccordance with thevpresentiinvention are those .portionsof petroleum crudev oils boiling between "360- 1F.--and'l50 The light gas oil is catalytically cracked preferably in a fluid catalyst unit in contact with a suitable cracking catalyst such as an acid-activated clay or a synthetic metal oxide gel such assilica-alumina, silica-magnesia or silica-alumina-.magnesia gels. The temperature of cracking` ofl this feed stock must be kept quite low, generally at between 800 and 850 F., preferably at .about..820825 F. It is also important that con- .version level be carefully controlled by controlling the feed rate (Volume of feed per volume of catalyst per hour). This should be so controlled that conversions of about -55 volume per cent, pref- `erablyabout of the light gas oil is converted to motor fuels boiling below 430 F. The product fof this mild cracking of light gas oil is fractionated ;and;az.Cc .to.230, tout isftaknifor blendingj-as .describe de below.

Thefheavygor regulargasoilslwhich may. be used in accordance` -withithe ,tiresentA invention vare vthoseportionso'f .petroleum crude; oilstboilingbe.- tween 500 F. and 900 F.

The heavy .gas oil.is catalytically cracked pref- .erably inaluidcatalyst unit in contact withan .active cracking catalyst such as an vacid-activated clay,l or a syntheticgmetaloxide .gel such as silica.- alumina,` silica-magnesia, .or-silica-aluminafmagnesia gels. The cracking .of Ithe heavy gas oil must bel effected atvhigh temperatures, i. e.- 950-1000 F. ypreferably at about 975 F. The conversion-level inthe heavygas oil cracking canbecontrolled bycontrolling the feedrate so that. from to 85 volumeper cent of the gas oil is converted to-liquid motor fuels boiling below 430 F. The product of; this cracking operation is fractionated and-a .230 F.-to 325 F. fractionis taken for blending purposes.

TheCe to230 F. fraction fromthe cracking ofthe light gasoil is blended 1, with the 230 to 325,F..fraction.from the cracking of the heavy .gas oil. The resultant blend has a substantially higher A. S. .T. M. .octane number than either-of .the aviation fuels obtainable from the feedstocks used and shows.a.3 Cv rich -mixture performance that is particularly outstanding.

The remaining fractions from .each ofthe above cracking operations boiling within the motor fuel range are combined `and passed to reforming means while the higher boiling stocks arerecycled, .the cycle stockvfrom..the :light gas oil cracking ,operation being preferably-combined with.v the cycle-stock from the heavy gas oil-cracking-operation and recycled tov the-'heavy ygas oil vcracking -stepwhereit=-is combined 4with-fresh heavy gas oil, and subjected to 'drastic-crackingconditions.

My invention is illustrated in the accompanying drawing in which the single figure is a diagrammatic ow plan of my process.

Referring to the drawing, I is a catalyst hopper for the supply of silica-alumina or other suitable cracking catalyst, preferably heated to a sufficient temperature to vaporize the respective oil stocks and bring them to reaction temperature. Light gas oil feed stock is supplied through line 2 and after the addition of catalyst through line 3 the mixture is introduced into reactor 4 wherein the cracking of the light gas oil feed to motor fuel is effected. Heavy gas oil feed stock is supplied through line 5 and is mixed With catalyst supplied through line 6 and the resultant mixture is introduced into reactor 'I wherein the heavy gas oil is A heavy coastal gas oil boiling between 500 F. and 900 F. was cracked in a fluid catalyst cracking unit in contact with silica-alumina catalyst at 975 F. (4.5 catalyst/ oil and 1.0 w./hr./w.) and at 81.7 volume per cent conversion (400 F. E. P.). This product was fractionated and a cut taken boiling between 230 and 325 F,

The Ofi-230 F. fraction from the light gas oil cracking and the 23o-325 F. fraction from the heavy gas oil cracking were blended (in production proportions) and sufficient isopentane Was added to attain a Reid vapor pressure of 7 pounds. The following table compares the inspections of the two cracked gasolines (with isopentane added to each to attain a Reid vapor pressure of 7 lbs.) with this blend.

(a) cc. tetraethyl lead per gallon. S is a reference fuel (isooctane or its equivalent) having a 100 octane number and M is a low octane number reference fuel (equivalent to 95% by volume of 2,2,4-trimethyl rentane .and 5% by volume of n-lieptane).

(S in M) is dilution of reference fuel of 100 N with low O. N. reference fuel necessary to match knocking tendency ci fuel of unknown O. N. Where fuel of unknown O. N. is higher than 100 O. N., its rating is given as equivalent to S fuel plus the cc. of tetraethyl lead required per gallon to match the knocking tendency of the fuel of the unknown O. N.

1 Duplicate determinations.

cracked to motor fuel. While I have shown a single hopper for the supply of catalyst to both feed stocks, it will be understood that separate hoppers may be provided, particularly if it is desired to use different catalysts for cracking the different feed stocks.

The reaction products are taken overhead from reactor il through line 8 and are separated in the fractionator into a Cra-230 F. fraction Withdrawn through line I a 23o-325 F. fraction withdrawn through line I I and a bottom fraction withdrawn through line I2.

The reaction products from reactor 'I are taken overhead through line I3 and are separated in the fractionator I4 into a Cri-230 F. fraction withdrawn through line I and preferably combined with the 230-325 F. fraction from fractionator 9 and passed to suitable reforming means. A 2SC-325 F. fraction is withdrawn from frac- `tionator Id through line I6 and is combined with the Cri-230 F. fraction from fractionator 9 to give the final high octane number gasoline in accordance with the present invention. The bottoms are withdrawn from fractionator I4 through .line Il' and preferably combined with the bottoms withdrawn from fractionator 9 through line I2 and recycled through line I8 back into reactor along with fresh feed supplied through line 5.

The following example is illustrative of the fpresent invention:

Example A renery light mixed gas oil (364 F. to 700 F.)

(8.3 catalyst/oil and 1.4 w./hr./w.) and at 48.6 volume per cent conversion (400 F. E. P.). The yresultant product was fractionated and a Cs to .230 F. fraction was taken.

twas cracked in a fluid catalyst cracking unit in contact with silica-alumina catalyst at 820 F.,

It may be readily seen from the foregoing inspection that the blend produced in accordance with the present invention has an extremely low acid heat, a higher ASTM Octane Number than either of the straight cracked gasolines, the 3C rich mixture performance being particularly outstanding.

The foregoing description contains a limited number of embodiments of this invention. It will be understood, however, that numerous variations are possible without departing from the scope of the following claims.

What I claim and desire to secure by Letters Patent is:

1. The process of producing high octane number gasolines which comprises catalytically cracking light gas oil at temperatures of about SOO-850 F. and at conversions of from 45-55 volume per cent, catalytically cracking heavy gas oil at temperatures of 9501000 F. and at conversions of from 55-85 volume per cent, taking a Cri-230 F. cut from the reaction product of the light gas oil cracking step and a 230325 F. cut from the relaction product of the heavy gas oil cracking step, and blending these cuts to produce a high octane number aviation gasoline.

2. The process of producing high octane number gasolines which comprises catalytically cracking light gas oil at temperatures of about 800-850o F. and at conversions of from 45-55 Volume per cent, catalytically cracking heavy gas oil at temperatures of 950-1000 F. and at conversions of from 55-85 volume per cent, taking a Cs-230 F. and a 230-325 F. cut from the reaction product of the light gas oil cracking step, taking a C6-230 F. and a 230-325" F. cut from the heavy gas oil cracking step and blending the Cri-230 F. cut from the cracked light gas oil with the 23o-325 F. cut from the cracked heavy gas oil to produce a high octane number aviation gasoline, and blending the 230-325" F. cut from the cracked light gas oil with the Cia-230 F. cut from the cracked heavy gas oil, and subjecting this mixture to a reforming operation.

3. The process of producing high octane number gasolines which comprises catalytically cracking light gas oil at temperatures of about 80G-850 F. and at conversions of from 45-55 volume per cent, catalytically cra-cking heavy gas oil at temperatures of 950-1000 F. and at conversions of from 55-85 volume per cent, taking a Cif-230 F. cut from the reaction product of the light gas oil cracking step and a 230-325 F. cut from the reaction product of the heavy gas oil cracking step, blending these cuts to produce a high octane number aviation gasoline and combining the bottoms from both fractionations with fresh heavy gas oil feed.

4. Ihe process of producing high octane number gasolines which comprises catalytically cracking light gas oil at temperatures of about 80G-850 F. and at conversions of from 45-55 volume per cent catalytically cracking heavy gas oil at temperatures of 950-1000 F. and at conversions of from 55-85 volume per cent, taking a Cri-230 F. and a 23o-325 F. cut from the reac- 6 tion product of the light gas oil cracking step, taking a Cta-230 F. and a ZBO-325 F. cut from the heavy gas oil cracking step, blending the Cs- 230 F. cut from the cracked light gas oil, With the 230-325 F. cut from the cracked heavy gas oil to produce a high octane number aviation gasoline, blending the 230-325 F. cut from the cracked light gas oil with the Ofi-230 F. cut from the cracked heavy gas oil, subjecting this mixture to a reforming operation and combining the bottoms from both fractionations with fresh heavy gas oil feed.

KENNETH M. PURDY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,235,133 Zimmerman Mar. 18, 1941 2,257,723 Arveson Oct. 7, 1941 2,289,716 Marschner July 14, 1942 2,303,107 Benedict Nov. 24, 1942 2,341,269 Day et al Feb. 8, 1944 2,423,637 Chandler July 8, 1947 2,432,912 Loeb Dec. 16, 1947 

